Vehicular opening-closing devices include opening-closing members for opening and closing a variety of openings of vehicles. The opening-closing device includes a trunk lid to open and close a trunk opening is known patent literature 1 below.
The opening-closing device disclosed in patent literature 1 includes a trunk opening formed in a rear part of a vehicle body, a trunk lid for opening/closing the trunk opening, a hinge arm through the trunk lid is swingably supported by the vehicle body, and a torsion bar urging the hinge arm in a direction to open the trunk lid.
More specifically, the torsion bar has one end connected to the vehicle body such that relative rotation of the one end to the vehicle body is limited. The torsion bar has an opposite end bent radially outwardly of the bar to form a generally crank-shaped configuration. The crank-shaped part has a distal end over which a resinous elastic pipe fits to be rotatable on a center of the pipe. The torsion bar has an urging force transmitted through the elastic pipe to the hinge arm, such that the hinge arm opens the trunk lid under the urging force.
When the torsion bar twists, the crank-shaped part twists in the same direction as the torsion bar. As a result, the elastic pipe fitting over the crank-shaped part can incline relative to the hinge arm. That is, the elastic pipe partially abuts on the hinge arm without uniformly contacting the hinge arm. For this reason, the urging force of the torsion bar acts on the hinge arm in a direction different from the direction to open the trunk lid. Such a phenomenon is obstructive to a smooth swing motion of the hinge arm and trunk lid. Additionally, the partial wear meaning that the elastic pipe partially wears, needs to be reduced as much as possible in order to improve the durability of the opening-closing device.
The trunk lid is preferably opened or closed at an optimal speed. To this end, a swing speed of the hinge arm needs to be set to an optimal value. Little or no sliding friction is produced between the hinge arm and the elastic pipe rotatably fitting over the torsion bar. Since the swing speed of the hinge arm depends on the urging force alone, the swing speed of the hinge arm is not necessarily set to the optimal value. To address this, it is thought that an additional mechanism for producing the friction force is newly provided in order to set the speed at which the trunk lid is opened or closed. However, the provision of such a mechanism is not expedient, because it increases the number of the parts of the device.